Sedimentary and neotectonic history of Lake Ohrid (Macedonia/Albania): acquisition and interpretation of new geophysical and geological data

位于马其顿/阿尔巴尼亚边境的奥赫里德湖是欧洲最古老的湖泊之一，可能在第三纪形成。奥赫里德湖拥有大量的地方性类群，是研究湖泊地质和生物进化之间联系的一流场所。奥赫里德湖早在1993年就被列为综合社区发展项目的目标地区，但缺乏适当的实地调查数据。在项目的第一阶段，进行了详细的陆上和海上调查，以揭示奥赫里德湖新近纪的沉积和构造历史，并评估深层钻探的潜力。新的地震数据显示了许多沉积特征，如阶地、斜坡、块体运动沉积和广泛的断层区，但也显示了一个深中央盆地，沉积物未受扰动。基底顶部的沉积物厚度高达近700米。根据声学数据，选择了五个主要地点作为潜在的钻探目标。陆上工作集中在详细的古应力分析，包括地貌构造，导致初步的应力历史与三个单独的阶段。项目第一阶段的成果是2009年1月提交给ICDP的钻探提案“关于奥赫里德湖过去物种形成条件的科学合作”的重要组成部分。本延长建议中计划的工作主要旨在i）研究奥赫里德湖的沉积历史，反映环境变化，ii）对奥赫里德湖及其周边地区进行详细的构造和断层分析。

Lake Ohrid at the Macedonian/Albanian border is one of the oldest lakes in Europe and was tectonically formed probably during the Tertiary. Lake Ohrid houses large concentrations of endemic taxa and represents a first class site to investigate the link between geological and biological evolution in lakes. Lake Ohrid was included as a target area of ICDP already in 1993 but appropriate site survey data were lacking. In the first phase of the project detailed on- and offshore investigations were carried out in order to reveal the Neogene depositional and tectonic history of Lake Ohrid and to evaluate the potential for deep drilling. The new seismic data show numerous sedimentary features such as terraces, clinoforms, mass movement deposits and areas of extensive faulting, but also a deep central basin with undisturbed sediments. Sediment thickness on top of the basement is up to almost 700m. Based on the acoustic data, five primary sites were chosen as potential drilling targets. The onshore work concentrated on detailed paleostress analyses including morphotectonics, which lead to a preliminary stress history with three individual phases. The results of the first project phase are essential parts of drilling proposal ‘Scientific Collaboration On Past Speciation Conditions in Lake Ohrid (SCOPSCO), which was submitted to ICDP in January 2009. Planned work in this prolongation proposal mainly aims in i) studying the depositional history of Lake Ohrid, reflecting environmental changes, and ii) performing detailed structural and fault analyses of Lake Ohrid and its surrounding.